Guide wire

ABSTRACT

A method of making a guide wire involves butting a connection end face at a proximal end of a first wire against a connection end face at a distal end of a second wire while applying voltage and a pressing force to weld together the first and second wires at a welded portion. The welded portion forms a projection that projects outwardly in an outer peripheral direction relative to portions of the first and second wire adjacent the projection. The outer dimension of the projection at the welded portion is adjusted so that upon completing adjusting the outer dimension of the projection the projection still projects outwardly in the outer peripheral direction relative to the portions of the first and second wire adjacent the projection.

This application is a continuation of U.S. application Ser. No.10/635,712 filed on Aug. 7, 2003 which serves as the basis for a claimfor priority under 35 U.S.C. § 120 in this application, the entirecontent of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a guide wire, particularly to a guidewire used to guide a catheter in a body lumen such as a blood vessel.

2. Description of the Related Art

Guide wires are used to guide a catheter in treatment of cites at whichopen surgeries are difficult or which require minimally invasiveness tothe body, for example, PTCA (Percutaneous Transluminal CoronaryAngioplasty), or in examination such as cardio-angiography. A guide wireused in the PTCA procedure is inserted, with the distal end projectingfrom the distal end of a balloon catheter, into the vicinity of a targetangiostenosis portion together with the balloon catheter, and isoperated to guide the distal end portion of the balloon catheter to thetarget angiostenosis portion.

A guide wire used to insert a catheter into a blood vessel complicatedlybent requires appropriate flexibility and restoring performance againstbending, pushability and torque transmission performance (genericallycalled “operationality”) for transmitting an operational force from theproximal end portion to the distal side, and kink resistance (oftencalled “resistance against sharp bending”). To obtain appropriateflexibility as one of the above-described performances, there has beenknown a guide wire configured such that a metal coil having flexibilityis provided around a small-sized core member at the distal end of theguide wire, or a guide wire including a core member made from asuperelastic material such as an Ni—Ti alloy for improving theflexibility and restoring performance.

Conventional guide wires include a core member that is substantiallymade from a single material. In particular, to enhance theoperationality of the guide wire, a material having a relatively highelastic modulus is used as the material of the core member. The guidewire including such a core member, however, has an inconvenience thatthe distal end portion of the guide wire becomes lower in flexibility.On the other hand, if a material having a relatively low elastic modulusis used as the material of the core member for increasing theflexibility of the distal end portion of the guide wire, theoperationality of the proximal end portion of the guide wire isdegraded. In this way, it has been regarded as difficult to satisfy bothrequirements associated with the flexibility and operationality by usinga core member made from a single material.

A guide wire intended to solve such a problem has been disclosed, forexample, in U.S. Pat. No. 5,171,383, wherein a Ni—Ti alloy wire is usedas a core member, and the distal side and the proximal side of the alloywire are heat-treated under different conditions in order to enhance theflexibility of the distal end portion of the alloy wire while enhancingthe rigidity of the proximal side of the alloy wire. Such a guide wire,however, has a problem that the control of the flexibility of the distalend portion by heat-treatment has a limitation. For example, even if itis successful to obtain a sufficient flexibility of the distal endportion of the alloy wire, it may often fail to obtain a sufficientrigidity on the proximal side of the alloy wire.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a guide wire capable ofimproving the strength of a joining portion between a first wire on thedistal side and a second wire on the proximal side, thereby enhancingthe operationality of the guide wire.

To achieve the above object, according to a first aspect of the presentinvention, there is provided a guide wire including a first wiredisposed on the distal side of the guide wire, and a second wiredisposed on the proximal side from the first wire, wherein the firstwire and the second wire are joined to each other by welding, and awelded portion formed by welding has a projection projecting in theouter peripheral direction.

According to a second aspect of the present invention, there is provideda guide wire including a first wire disposed on the distal side of theguide wire, and a second wire disposed on the proximal side from thefirst wire, the second wire having a rigidity higher than that of thefirst wire, wherein the first wire and the second wire are joined toeach other by welding, a welded portion formed by welding has aprojection projecting in the outer peripheral direction, the second wirehas a first portion provided in the vicinity of the distal end of thesecond wire and a second portion provided on the proximal side from thefirst portion, and the first portion has a rigidity lower than that ofthe second portion.

Each of the guide wires according to the first and second aspects of thepresent invention may be further configured as follows.

The guide wire may further include a cover layer disposed over at leastthe welded portion.

The projection may be visible under fluoroscopy.

The guide wire may further include a spiral coil covering at least adistal end portion of the first wire.

The proximal end of the coil may abut on the projection.

The height of the projection may be in a range of 0.01 to 0.3 mm.

The welding is performed by a butt resistance welding process.

Each of the connection end face of the first wire to the second wire andthe connection end face of the second wire to the first wire may benearly perpendicular to the axial direction of the first and secondwires.

The guide wire may have an outer-diameter gradually reducing portionwith its outer diameter gradually reduced in the direction toward thedistal end.

The outer-diameter gradually reducing portion may be provided on thedistal side from the welded portion.

The outer-diameter gradually reducing portion may be provided on theproximal side from the welded portion.

The first wire has an outer diameter being nearly constant over theentire length except for the projection.

The first wire may be made from a material having an elastic modulussmaller than that of the second wire.

The first wire may be made from a superelastic alloy.

The second wire may be made from a stainless steel.

The second wire may be made from a Co-based alloy.

The Co-based alloy may be a Co—Ni—Cr alloy.

The guide wire may have at least one projection projecting in the outerperipheral direction in addition to the projection provided at thewelded portion.

The proximal side and the distal side of the projection may be formedinto shapes asymmetric to each other with respect to the welded surfaceof the welded portion.

A portion, located in the vicinity of the welded portion between thefirst wire and the second wire may have e thinned portion, and theprojection may be provided on the thinned portion.

As described above, according to the present invention, by providing thefirst wire disposed on the distal side and the second wire disposed onthe proximal side from the first wire, it is possible to provide a guidewire having good operationality. In particular, by providing the firstwire having a high flexibility and the second wire made from a materialhaving an elastic modulus larger than that of the first wire, it ispossible to provide a guide wire having the distal end portion having ahigh flexibility and the proximal end portion having a high rigidity,thereby improving the pushing performance, torque transmissionperformance, and trackability.

Since the first wire and the second wire are joined to each other bywelding and the projection is formed at the welded portion, it ispossible to the joining strength of the joining portion (weldedportion), and hence to certainly transmit a torsional torque and apushing force from the second wire to the first wire.

Since the projection is provided at the welded portion between the firstwire and the second wire, the welded portion becomes easily visibleunder fluoroscopy, to improve the operationality of the guide wire and acatheter used together with the guide wire, thereby shortening theoperation time and improving the safety.

The provision of the projection is also effective in reducing thecontact area of the guide wire with the inner wall of a catheter usedtogether with the guide wire, to reduce the friction resistance of theguide wire during movement of the guide wire relative to the catheter,thereby improving the sliding performance. As a result, it is possibleto enhance the operationality of the guide wire in the catheter.

In the case of providing the cover layer made from a material capable ofreducing the friction, it is possible to improve the sliding performanceof the guide wire in the catheter, thereby further enhancing theoperationality of the guide wire. Since the sliding resistance of theguide wire is reduced, it is possible to more certainly prevent kink(sharp bending) or torsion, especially, of a portion in the vicinity ofthe welded portion.

By changing materials used for the cover layer at respective portions,it is possible to enhance the sliding resistance at each of the portionsand hence to expand the versability for an operator.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects, features, and advantages of the presentinvention will become more apparent from the following detaileddescription in conjunction with the accompanying drawings, wherein:

FIG. 1 is a longitudinal sectional view showing a first embodiment of aguide wire of the present invention;

FIGS. 2A to 2C are views showing steps of a procedure for connecting afirst wire and a second wire of the guide wire shown in FIG. 1;

FIG. 3 is a typical view illustrating an example of how to use the guidewire of the present invention;

FIG. 4 is a typical view illustrating the example of how to use theguide wire of the present invention;

FIG. 5 is a longitudinal sectional view showing a second embodiment ofthe guide wire of the present invention;

FIG. 6 is a longitudinal sectional view showing a third embodiment ofthe guide wire of the present invention;

FIG. 7 is a longitudinal sectional view showing a modification of theguide wire of the present invention;

FIG. 8 is a longitudinal sectional view showing another modification ofthe guide wire of the present invention;

FIG. 9 is a longitudinal sectional view showing a further modificationof the guide wire of the present invention;

FIG. 10 is a longitudinal sectional view showing a modification of theshape of a projection of the guide wire of the present invention;

FIG. 11 is a longitudinal sectional view showing another modification ofthe shape of a projection of the guide wire of the present invention;

FIG. 12 is a longitudinal sectional view showing a further modificationof the shape of a projection of the guide wire of the present invention;

FIG. 13 is a longitudinal sectional view showing a further modificationof the shape of a projection of the guide wire of the present invention;and

FIG. 14 is a longitudinal sectional view showing a modification of theshape of portion, in the vicinity of a welded portion, of the guide wireof the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A guide wire of the present invention will now be described in detail byway of preferred embodiments shown in the accompanying drawings.

FIG. 1 is a longitudinal sectional view of a first embodiment of a guidewire of the present invention, and FIGS. 2A to 2C are views showing aprocedure for joining a first wire and a second wire of the guide wireshown in FIG. 1 to each other. For convenience of description, the rightside in FIG. 1 is taken as the “proximal side” and the left side in FIG.1 is taken as the “distal side”. It is to be noted that in FIG. 1 andFIGS. 2A to 2C (and in FIGS. 5 to 9 to be described later), for easyunderstanding, the dimension of the guide wire in the thicknessdirection is exaggeratedly enlarged while the dimension of the guidewire in the length direction is shortened, and therefore, the ratio ofthe thickness to the length is significantly different from the actualratio.

A guide wire 1A shown in FIG. 1, which is of a type used to be insertedin a catheter, includes a first wire 2 disposed on the distal side, asecond wire 3 disposed on the proximal side from the first wire 2, and aspiral coil 4. The entire length of the guide wire 1A is notparticularly limited but is preferably in a range of about 200 to 5,000mm. The outer diameter of the guide wire 1A is not particularly limitedbut is preferably in a range of about 0.2 to 1.2 mm.

The first wire 2 is configured as a wire member having elasticity. Thelength of the first wire 2 is not particularly limited but is preferablyin a range of about 20 to 1,000 mm.

According to this embodiment, the first wire 2 has an outer-diametergradually reducing portion 16 with its outer diameter gradually reducedin the direction toward the distal end. This gradually reduces therigidity (flexural rigidity, torsional rigidity) of the first wire 2 inthe direction toward the distal end. As a result, the distal end portionof the guide wire 1A has a high flexibility, to improve trackability andsafety to a blood vessel and to prevent sharp-bending and the like.

The length of the outer-diameter gradually reducing portion 16 (denotedby character L₁ in FIG. 1) is not particularly limited but is preferablyin a range of about 10 to 1,000 mm, more preferably, about 20 to 300 mm.By setting the length L₁ in the above range, the change in rigidity inthe longitudinal direction becomes more moderate (or smooth).

According to this embodiment, the outer-diameter gradually reducingportion 16 is tapered such that the outer diameter is continuouslyreduced with a nearly constant reduction ratio in the direction towardthe distal end. In other words, the taper angle of the outer-diametergradually reducing portion 16 is kept nearly constant along thelongitudinal direction. In the guide wire 1A according to thisembodiment, therefore, the change in rigidity becomes more moderate (orsmooth) along the longitudinal direction. Unlike such a configuration,the reduction ratio of the outer diameter of the outer-diametergradually reducing portion 16 (taper angle of the outer-diametergradually reducing portion 16) may be changed along the longitudinaldirection. For example, portions in each of which the reduction ratio ofthe outer diameter is relatively large and portions in each of which thereduction ratio of the outer diameter is relatively small may bealternately repeated by a plurality of numbers. In this case, theouter-diameter gradually reducing portion 16 may have a portion in whichthe reduction ratio of the outer diameter in the direction toward thedistal end becomes zero.

The material for forming the first wire 2 is not particularly limitedbut may be selected from metal materials, for example, stainless steelssuch as SUS304, SUS303, SUS316, SUS316L, SUS316J1, SUS316J1L, SUS405,SUS430, SUS434, SUS444, SUS429, SUS430F, and SUS302 and alloys havingpseudo-elasticity, for example, superelastic alloys. Of these materials,superelastic alloys are preferable. Superelastic alloys are relativelyflexible, good in restoring performance, and no or less plasticdeforming. Accordingly, if the first wire 2 is made from a superelasticalloy, the guide wire 1A including such a first wire 2 has, at itsdistal portion, a high flexibility and a high restoring performanceagainst bending, and a high trackabiligy to a blood vessel complicatedlycurved or bent, to thereby enhance the operationality of the guide wire1A. Even if the first wire 2 is repeatedly deformed, that is, curved orbent, the first wire 2 is no or less plastic deforming because of itshigh restoring performance. This prevents degradation of theoperationality due to the plastic deforming of the first wire 2 duringuse of the guide wire 1A.

Pseudo-elastic alloys include those of a type in which the stress-straincurve in a tensile test has any shape, those of a type in which atransformation point such as As, Af, Ms, or Mf can be significantlymeasured or not measured, and all of a type in which the shape isgreatly deformed by stress and then restored nearly to an original shapeby removal of stress.

Examples of superelastic alloys include Ni—Ti alloys such as an Ni—Tialloy containing Ni in an amount of 49-52 atomic %, a Cu—Zn alloycontaining Zn in an amount of 38.5 to 41.5 wt %, a Cu—Zn—X alloycontaining X in an amount of 1 to 10 wt % (X: at least one kind selectedfrom a group consisting of Be, Si, Sn, Al, and Ga), and an Ni—Al alloycontaining Al in an amount of 36 to 38 atomic %. Of these materials, theNi—Ti alloy is preferable.

The distal end of the second wire 3 is joined to the proximal end of thefirst wire 2. The second wire 3 is a wire member having elasticity. Thelength of the second wire 3 is not particularly limited but may be in arange of about 20 to 4,800 mm.

The second wire 3 is generally made from a material having an elasticmodulus (Young's modulus or modulus of longitudinal elasticity, modulusof rigidity or modulus of transverse elasticity, or bulk modulus)different from that of the first wire 2. The guide wire 1A obtained byjoining the first wire 2 and the second wire 3 different in elasticmodulus to each other exhibits desired operationality.

The material for forming the second wire 3 is not particularly limitedbut may be selected from metal materials, for example, stainless steels(all kinds specified in SUS, for example, SUS304, SUS303, SUS316,SUS316L, SUS316J1, SUS316J1L, SUS405, SUS430, SUS434, SUS444, SUS429,SUS430F, and SUS302), piano wire steels, cobalt alloys, and alloyshaving pseudo-elasticity.

In particular, cobalt alloys are preferably used for the second wire 3.This is because the second wire 3 made from a cobalt alloy has a highelastic modulus and an appropriate elastic limit. Such a second wire 3exhibits a high torque transmission performance, thereby hardly causinga problem associated with buckling or the like. Any type of cobalt alloymay be used insofar as it contains cobalt. In particular, a cobalt alloycontaining cobalt as a main component (that is, a cobalt-based alloycontaining cobalt in an amount [in wt %] being the largest among thecontents of all components of the alloy) is preferably used, andfurther, a Co—Ni—Cr alloy is more preferable. The use of the cobaltalloy having such a composition as the material for forming the secondwire 3 is effective to further enhance the above-described effects. Thecobalt alloy having such a composition is also advantageous in thatsince the alloy exhibits plasticity in deformation at room temperature,the second wire 3 made from such a cobalt alloy is easily deformableinto a desired shape, for example, during use of the guide wire. Afurther advantage of the cobalt alloy having such a composition is asfollows: namely, since the second wire 3 made from such a cobalt alloyhas a high elastic modulus and is cold-formable even if it exhibits ahigh elastic limit, the second wire 3 can be thinned while sufficientlypreventing occurrence of buckling, and therefore, can exhibit a highflexibility and a high rigidity enough to be inserted into a desiredsite.

The Co—Ni—Cr alloy is exemplified by an alloy containing 28-50 wt % ofCo, 10-30 wt % of Ni, and 10-30 wt % of Cr, the balance being Fe. Inthis alloy, part of any component may be substituted by another element(substitution element). The incorporation of such a substitution elementexhibits an effect inherent to the kind thereof. For example, theincorporation of at least one kind selected from a group consisting ofTi, Nb, Ta, Be, and Mo further improves the strength of the second wire3. In the case of incorporating one or more substitution elements otherthan Co, Ni, and Cr, the total content of the substitution elements ispreferably in a range of 30 wt % or less.

For example, part of Ni may be substituted by Mn, which is effective tofurther improve the workability. Part of Cr may be substituted by Moand/or W, which is effective to further improve the elastic limit. Ofthe Co—Ni—Cr alloys, a Co—Ni—Cr—Mo alloy is particularly preferable.

Examples of compositions of the Co—Ni—Cr alloys include (1) 40 wt %Co-22 wt % Ni-25 wt % Cr-2 wt % Mn-0.17 wt % C-0.03 wt % Be—Fe(balance), (2) 40 wt % Co-15 wt % Ni-20 wt % Cr-2 wt % Mn-7 wt % Mo-0.15wt % C-0.03wt % Be—Fe (balance), (3) 42 wt % Co-13 wt % Ni-20 wt %Cr-1.6 wt % Mn-2 wt % Mo-2.8 wt % W-0.2 wt % C-0.04 wt % Be—Fe(balance), (4) 45 wt % Co-21 wt % Ni-18 wt % Cr-1 wt % Mn-4 wt % Mo-1 wt% Ti-0.02 wt % C-0.3 wt % Be—Fe (balance), and (5) 34 wt % Co-21 wt %Ni-14 wt % Cr-0.5 wt % Mn-6 wt % Mo-2.5 wt % Nb-0.5 wt % Ta—Fe(balance). The wording “Co—Ni—Cr alloy” used herein is the conceptionincluding these Co—Ni—Cr alloys.

If a stainless steel is used as the material for forming the second wire3, the pushability and torque transmission performance can be furtherenhanced.

The first wire 2 and the second wire 3 may be made from differentalloys, and particularly, the first wire 2 is preferably made from amaterial having an elastic modulus smaller than that of the material ofthe second wire 3. With this configuration, the distal end portion ofthe guide wire 1A has a high flexibility, and the proximal end portionof the guide wire 1A has a high rigidity (flexural rigidity, torsionalrigidity). As a result, the guide wire 1A has a high pushability and ahigh torque transmission performance, thereby enhancing theoperationality, and also exhibits, on the distal side, a highflexibility and a high restoring performance, thereby improvingtrackability and safety to a blood vessel.

As one preferred combination of materials of the first wire 2 and thesecond wire 3, the first wire 2 is made from a superelastic alloy andthe second wire 3 is made from a Co—Ni—Cr alloy or a stainless steel.With this configuration, the above-described effects become moresignificant.

In the configuration shown FIG. 1, the second wire 3 has a nearlyconstant outer diameter over the entire length; however, the second wire3 may have portions with outer diameters changed in the longitudinaldirection.

From the viewpoint of enhancing the flexibility and restoringperformance of the distal end portion of the first wire 2, it ispreferred to use a Ni—Ti alloy as the superelastic alloy for forming thefirst wire 2.

The coil 4 is a member formed by spirally winding a wire, particularly afine wire, and is provided so as to cover the distal end portion of thefirst wire 2. In the configuration shown in FIG. 1, the distal endportion of the first wire 2 is disposed in an approximately axiallycenter portion of the coil 4 in such a manner as to be not in contactwith the inner surface of the coil 4. It is to be noted that in theconfiguration shown in FIG. 1, the coil 4 is loosely disposed in such amanner that a slight gap remains between adjacent spirally wound wireportions in a state that no external force is applied to the coil 4;however, the coil 4 may be tightly disposed in such a manner that no gapremains between the adjacent spirally wound wire portions in a statethat no external force is applied to the coil 4.

The coil 4 may be made from a metal material such as a stainless steel,a superelastic alloy, a cobalt alloy, a noble metal such as gold,platinum, or tungsten, or an alloy containing such a noble metal. Inparticular, the coil 4 is preferably made from a radiopaque materialsuch as a noble metal. If the coil 4 is made from such a radiopaquematerial, the guide wire 1A can exhibit an X-ray contrast performance.This makes it possible to insert the guide wire 1A in a living bodywhile confirming the position of the distal end portion of the guidewire 1A under fluoroscopy. The distal side and proximal side of the coil4 may be made from different alloys. For example, the distal side of thecoil 4 may be formed of a coil made from a radiopaque material and theproximal side of the coil 4 be formed of a coil made from a relativelyradiolucent material such as a stainless material. The entire length ofthe coil 4 is not particularly limited but may be in a range of about 5to 500 mm.

The proximal end portion and the distal end portion of the coil 4 arefixed to the first wire 2 by a fixing material 11 and a fixing material12, respectively, and an intermediate portion (close to the distal end)of the coil 4 is fixed to the first wire 2 by a fixing material 13. Eachof the fixing materials 11, 12, and 13 is a solder (brazing material).Alternatively, each of the fixing materials 11, 12, and 13 may be anadhesive. In addition, in place of using the fixing material, the coil 4may be fixed to the first wire 2 by welding. To prevent damage of theinner wall of a blood vessel, the leading end surface of the fixingmaterial 12 is preferably rounded.

According to this embodiment, since the first wire 2 is partiallycovered with the coil 4, the contact area of the first wire 2 with theinner wall of a catheter used together with the guide wire 1A is small,with a result that it is possible to reduce the sliding resistance ofthe guide wire 1A in the catheter. This is effective to further improvethe operationality of the guide wire 1A.

In this embodiment, the wire having a circular shape in cross-section isused for the coil 4; however, the cross-sectional shape of the wire usedfor the coil 4 may be another shape such as an elliptic shape or aquadrilateral shape (especially, rectangular shape).

In the guide wire 1A, the first wire 2 and the second wire 2 are joinedto each other by welding. A welded portion (joining portion) 14 betweenthe first wire 2 and the second wire 3 has a high joining strength.

In particular, according to the present invention, a projection 15projecting in the outer peripheral direction is formed at the weldedportion 14. The formation of such a projection 15 is effective toenlarge the joining area between the first wire 2 and the second wire 3,to significantly enhance the joining strength between the first wire 2and the second wire 3. As a result, the guide wire 1A is advantageous inthat the torsional torque and pushing force can be certainly transmittedfrom the second wire 3 to the first wire 2.

The formation of the projection 15 has another advantage in that thewelded portion 14 between the first wire 2 and the second wire 3 may beeasily visible under fluoroscopy. This may make it possible to easily,certainly recognize the advancing state of the guide wire 1A and acatheter in a blood vessel by checking the fluoroscopic image of theprojection 15, and hence to shorten the operation time and improve thesafety.

In the configuration shown in FIG. 1, each of one side (upper side) andthe other side (lower side) of the projection 15 is formed into anapproximately circular-arc shape in longitudinal cross-section, and thewelded portion 14 is located at the maximum outer-diameter portion ofthe projection 15. With this configuration, the area of the weldedsurface of the welded portion 14 becomes large, to obtain a higherjoining strength (welding strength). Another advantage is that when theguide wire 1A is bent, since the welded surface of the welded portion 14is located at the maximum outer-diameter portion, stress isdisconcentrated to a small outer-diameter portion closed to theprojection 15. This makes it possible to prevent stress concentration atthe welded portion 14. It is to be noted that according to the presentinvention, the shape of the projection 15 and the location of the weldedportion 14 relative to the projection 15 are not limited to thosedescribed above.

As described above, the first wire 2 and the second wire 3 are generallymade from materials having different elastic moduli. Accordingly,because of provision of the projection 15, an operator can easily,certainly, recognize a portion, at which the elastic modulus isrelatively largely changed, of the guide wire 1A. This enhances theoperationality of the guide wire 1A, to shorten the operation time andimprove the safety.

The formation of the projection 15 has a further advantage in makingsmall the contact area of the guide wire 1A with the inner wall of acatheter used together with the guide wire 1A, to reduce the slidingresistance of the guide wire 1A when the guide wire 1A is moved relativeto the catheter, thus improving the sliding performance of the guidewire 1A. This enhances the operationality of the guide wire 1A in thecatheter.

The height of the projection 15 is not particularly limited but ispreferably in a range of 0.001 to 0.3 mm, more preferably, 0.01 to 0.05mm. If the height of the projection 15 is less than the lower limit, itmay fail to sufficiently obtain the above-described effects depending onthe materials of the first wire 2 and the second wire 3. If the heightof the projection 15 is more than the upper limit, since the innerdiameter of a lumen, in which the guide wire 1A is to be inserted, of aballoon catheter is fixed, the outer diameter of the second wire 3 onthe proximal side must be thin relative to the height of the projection15, with a result that it may become difficult to ensure sufficientphysical properties of the second wire 3.

In this embodiment, a connection end face 21 of the first wire 2 to thesecond wire 3 and a connection end face 31 of the second wire 3 to thefirst wire 2 are each formed into a plane nearly perpendicular to theaxial (longitudinal) direction of both the wires 2 and 3. Thissignificantly facilitates working for forming the connection end faces21 and 31, to achieve the above-described effects without complicatingthe steps for producing the guide wire 1A.

It is to be noted that each of the connection end faces 21 and 31 may betilted relative to the plane perpendicular to the axial (longitudinal)direction of both the wires 2 and 3, or formed into a recessed or raisedshape.

The method of welding the first wire 2 and the second wire 3 to eachother is not particularly limited but is generally exemplified by spotwelding using laser or butt resistance welding such as butt seamwelding. In particular, to ensure a high joining strength of the weldedportion, butt resistance welding is preferable.

The procedure of joining the first wire 2 and the second wire 3 to eachother by butt seam welding as one example of butt resistance weldingwill be described with reference to FIGS. 2A to 2C. FIGS. 2A to 2C showsteps 1 to 3 of the procedure of joining the first wire 2 and the secondwire 3 to each other by butt seam welding.

In the step 1, the first wire 2 and the second wire 3 are fixed(mounted) to a butt welder (not shown).

In the step 2, the connection end face 21 on the proximal side of thefirst wire 2 and the connection end face 31 on the distal side of thesecond wire 3 are butted to each other while a specific voltage isapplied thereto by the butt welder. With this operation, a fused layer(welded surface) is formed at the contact portion, whereby the firstwire 2 and the second wire 3 are strongly joined to each other. At thistime, the projection 15 projecting in the outer peripheral direction isformed on the welded portion 14. The size (height) of the projection 15can be controlled by adjusting, for example, an applied voltage and apressing force applied between the first wire 2 and the second wire 3.Alternatively, the size (height) of the projection 15 may be adjusted,for example, by grinding.

In the step 3, the distal side of the first wire 2 is ground, to formthe outer-diameter gradually reducing portion 16 with its outer-diametergradually reduced in the direction toward the distal end.

FIGS. 3 and 4 are views showing the operational state of the guide wire1A of the present invention during use in the PTCA process.

In FIGS. 3 and 4, reference numeral 40 denotes an aortic arch, 50 is aright coronary artery of a heart, 60 is an ostium of the right coronaryartery 50, and 70 is a target angiostenosis portion. Further, referencenumeral 30 denotes a guiding catheter for certainly guiding the guidewire 1A from an arteria fermoralis into the right coronary artery 50,and 20 is a balloon catheter having at its distal end an expandable andcontractible balloon 201 for dilating the target angiostenosis portion70.

As shown in FIG. 3, the guide wire 1A is moved in such a manner that thedistal end thereof projecting from the distal end of the guidingcatheter 30 is inserted in the right coronary artery 50 through theostium 60 of the right coronary artery 50. The guide wire 1A is furtheradvanced, and is stopped when the distal end thereof passes the targetangiostenosis portion 70 in the right coronary artery 50. In this state,an advance path of the balloon catheter 20 is ensured. At this time, thewelded portion 14 of the guide wire 1A is located in the living body,more specifically, in the vicinity of the distal portion of the aorticarch 40.

As shown in FIG. 4, the balloon catheter 20 is inserted around the guidewire 1A from the proximal side of the guide wire 1A. The ballooncatheter 20 is then advanced in such a manner that the distal endthereof projects from the distal end of the guiding catheter 30, goesahead along the guide wire 1A, and enters the right coronary artery 50from the ostium 60 of the right coronary artery 50. The balloon catheter20 is stopped when the balloon 201 reaches a position corresponding tothat of the target angiostenosis portion 70.

A fluid for inflating the balloon 201 is injected in the ballooncatheter 20 from the proximal side of the balloon catheter 20, toinflate the balloon 201, thereby dilating the target angiostenosisportion 70. As a result, deposits such as cholesterol adhering on thearterial wall of the target angiostenosis portion 70 are physicallycompressed against the arterial wall, to eliminate blocking of bloodflow.

FIG. 5 is a longitudinal sectional view showing a second embodiment ofthe guide wire of the present invention. The second embodiment of theguide wire of the present invention will now be described with referenceto FIG. 5, principally, about differences from the previous embodiment,with the description of the same features omitted.

According to a guide wire 1B in this embodiment, an outer-diametergradually reducing portion 16 is formed on a second wire 3, and a firstwire 2 has an outer diameter being nearly constant nearly over theentire length except for a projection 15. In other words, in the guidewire 1B, the outer-diameter gradually reducing portion 16 is provided onthe proximal side from the welded portion 14.

In the guide wire 1B, the proximal end of a coil 4 abuts on theprojection 15.

FIG. 6 is a longitudinal sectional view showing a third embodiment ofthe guide wire of the present invention. The third embodiment of theguide wire of the present invention will now be described with referenceto FIG. 6, principally, about differences from the previous embodiments,with the description of the same features omitted.

According to a guide wire 1F in this embodiment, a first wire 2 has anouter-diameter gradually reducing portion 16 and an outer-diametergradually reducing portion 18 provided on the proximal side from theouter-diameter gradually reducing portion 16. In this way, according tothe guide wire of the present invention, outer-diameter graduallyreducing portions may be formed at a plurality of positions of the firstwire 2 (or second wire 3).

In the guide wire 1F, the second wire 3 has an outer-diameter graduallyreducing portion 16′ located in the vicinity of the distal end. To bemore specific, the second wire 3 has a first portion provided in thevicinity of the distal end and a second portion provided on the proximalside from the first portion, wherein the second portion has rigidityhigher than that of the first portion. In the guide wire 1F, the firstportion is configured as the outer-diameter gradually reducing portion16′. This gives rise to an effect of smoothly changing transition ofelasticity from the second wire 3 to the first wire 2. The first portionmay be configured as a combination of the outer-diameter graduallyreducing portion 16′ and an outer-diameter constant portion provided onthe distal side from the outer-diameter gradually reducing portion 16′.The outer-diameter constant portion preferably has a rigidity beingnearly equal to that of the proximal portion of the first wire 2.

The guide wire 1F has a cover layer 7 on the outer surface (outerperipheral surface) side. In this way, the guide wire of the presentinvention may be configured to have a cover layer that covers the wholeor part of the outer surface (outer peripheral surface). Such the coverlayer 7 is formed for satisfying various purposes, one of which is toreduce the friction (sliding friction) of the guide wire 1F forimproving the sliding performance of the guide wire 1F, therebyenhancing the operationality of the guide wire 1F.

To satisfy the above-described purpose, the cover layer 7 is preferablymade from a material capable of reducing the friction of the guide wire1F. With this configuration, since the friction resistance (slidingresistance) of the guide wire 1F against the inner wall of a catheterused together with the guide wire 1F is reduced, the sliding performanceof the guide wire 1F is improved, to enhance the operationality of theguide wire 1F in the catheter. Further, since the sliding resistance ofthe guide wire 1F is reduced, it is possible to more certainly prevent,at the time of movement and/or rotation of the guide wire 1F in thecatheter, kink (sharp bending) or torsion of the guide wire 1F,particularly, in the vicinity of a welded portion of the guide wire 1F.

Examples of the materials capable of reducing the friction of the guidewire 1F include polyorefins such as polyethylene and polypropylene,polyvinyl chloride, polyesters (such as PET and PBT), polyamide,polyimide, polyurethane, polystyrene, polycarbonate, silicone resins,fluorocarbon resins (such as PTFE and ETFE), silicone rubbers, variouskinds of elastomers (for example, thermoplastic elastomers such aspolyamide-based elastomer and polyester-based elastomer), and compositematerials thereof. In particular, a fluorocarbon resin or a compositematerial thereof is preferable, and PTFE is more preferable.

According to this embodiment, a hydrophilic material or a hydrophobicmaterial can be also used as another preferred example of the materialcapable of reducing the friction of the guide wire 1F. In particular,the hydrophilic material is preferable.

Examples of the hydrophilic materials include a cellulose based polymer,a polyethylene oxide based polymer, a maleic anhydride based polymer(for example, a maleic anhydride copolymer such asmethylvinylether-maleic anhydride copolymer), an acrylic amide basedpolymer (for example, polyacrylic amide or polyglycidylmethacrylate-dimethyl acrylic amide [PGMA-DMAA] block copolymer),water-soluble nylon, polyvinyl alcohol, and polyvinyl pyrolidone.

In many cases, the hydrophilic material can exhibit a lubricatingperformance in a wet (water-absorbing) state. The use of the cover layer7 made from such a hydrophilic material is effective to reduce thefriction resistance (sliding resistance) of the guide wire 1F againstthe inner wall of a catheter used together with the guide wire 1F, toimprove the sliding performance of the guide wire 1F, thereby enhancingthe operationality of the guide wire 1F in the catheter.

The cover layer 7 may be formed in such a manner as to cover the wholeor part of the guide wire 1F in the longitudinal direction. Inparticular, the cover layer 7 is preferably formed so as to cover awelded portion 14, and specifically, formed in a region including thewelded portion 14.

The cover layer 7 covers the outer-diameter gradually reducing portion16′ and a projection 15 in such a manner as to have a substantiallyconstant outer diameter. The wording “substantially constant outerdiameter” used herein means an outer diameter that is smoothly changedto such a degree as not to cause any hindrance in use of the guide wire1F.

The thickness (in average) of the cover layer 7 is not particularlylimited but is preferably in a range of about 1 to 20 μm, morepreferably, about 2 to 10 μm. If the thickness of the cover layer 7 isless than the lower limit, the effect obtained by formation of the coverlayer 7 may be not sufficiently achieved and the cover layer 7 may beoften peeled. If the thickness of the cover layer 7 is more than theupper limit, the physical properties of the wire may be obstructed andthe cover layer 7 may be often peeled.

According to the present invention, the outer peripheral surface of theguide wire body (including the first wire 2, the second wire 3, and coil4) may be subjected to a treatment (such as chemical treatment or heattreatment) for improving the adhesion characteristic of the cover layer7, or may be provided with an intermediate layer for improving theadhesion characteristic of the cover layer 7.

The cover layer 7 may have a nearly constant composition or differentcompositions at respective portions. For example, the cover layer 7 mayhave a first region (first cover layer) for covering at least the coil 4and a second region (second cover layer) on the proximal side from thefirst region, wherein the first cover layer and the second cover layerbe made from different materials. Preferably, the first cover layer ismade from a hydrophilic material and the second cover layer is made froma hydrophobic material. As shown in the figure, the first cover layerand the second layer may be formed so as to be continuous to each otherin the longitudinal direction. Alternatively, the proximal end of thefirst cover layer may be separated from the distal end of the secondcover layer, or the first cover layer may be partially overlapped to thesecond cover layer.

Such a cover layer (including the coating made from the hydrophilicmaterial or the hydrophobic material) may be provided on the guide wireaccording to each of the first and second embodiments.

While the guide wire of the present invention has been described by wayof the embodiments shown in the FIGS. 1 to 6, the present invention isnot limited thereto. Each of the composing elements of the guide wire ofthe present invention may be replaced with a composing element havingany other configuration exhibiting the similar effect, and may beprovided with any other additional element.

For example, according to the guide wire of the present invention,projections projecting in the outer peripheral direction may be providedin addition to the above-described projection 15 provided at the weldedportion 14.

FIGS. 7 and 8 show such modifications of the guide wire of the presentinvention, in each of which projections 17 projecting in the outerperipheral direction are provided in addition to the projection 15provided at the welded portion 14. The formation of these projections 17is effective to further reduce the contact area of the guide wire withthe inner wall of a catheter used together with the guide wire and henceto further reduce the friction resistance of the guide wire when theguide wire is moved relative to the catheter. This makes it possible tofurther improve the sliding performance of the guide wire and hence tofurther enhance the operationality of the guide wire in the catheter.

In the previous embodiments, the guide wire has the two wires, that is,the first wire 2 and the second wire 3, which are joined to each otheronly at one joining portion; however, the guide wire of the presentinvention may have two or more wires joined to each other at two or morejoining portions. In other words, the guide wire of the presentinvention may have one or two wires other than the first wire 2 and thesecond wire 3.

FIG. 9 shows such a modification of the guide wire of the presentinvention. As shown in this figure, a guide wire 1E has a third wire 5on the proximal side of the second wire 3. With this configuration, itis possible to more precisely set characteristics, such as elasticity,of respective portions of the guide wire in the longitudinal direction,and hence to further improve the operationality of the entire guidewire.

In this guide wire 1E, the second wire 3 is joined to the third wire 5by means of a welded portion 14 similar to the welded portion 14described in the previous embodiments. In this case, preferably, aprojection 17 similar to the projection 15 described in the previousembodiments is formed on the welded portion 14.

In addition, although the welded portion 14 is located on the proximalside from the proximal end of the coil 4 in the previous embodiments,the welded portion 14 may be located on the distal side from theproximal end of the coil 4.

According to the present invention, the shape of the projection 15 or 17formed on the welded portion 14 may be variously modified. Examples ofthe shapes of the projection 15 or 17 will be described below withrespect to FIGS. 10 to 13.

FIG. 10 shows one modification of the projection of the guide wire ofthe present invention. As shown in this figure, each of one side (upperside in the figure) and the other side (lower side in the figure) of aprojection 15 is formed into a trapezoidal shape in longitudinalcross-section. In this way, according to the previous embodiments, eachof the one side and the other side of the projection 15 is formed intoan approximately circular-arc shape curved in a projecting manner inlongitudinal cross-section; however, according to the present invention,each of the one side and the other side of the projection 15 may beformed into another shape, for example, a non-circular (non-circulararc) shape such as a trapezoidal shape or a triangular shape inlongitudinal cross-section.

In the projection 15 shown in FIG. 10, a portion, in the vicinity of thewelded portion 14, of the projection 15 (which portion is composed oftwo regions on the proximal side and the distal side from the weldedportion 14, that is, which portion is equivalent to the upper base ofthe trapezoidal shape) has a nearly constant outer diameter. The weldedportion 14 is located at a portion, having the maximum outer diameter,of the projection 15, and in this case, located at an approximatelycenter of such a portion having a nearly constant outer diameter. Withthis configuration, it is possible to prevent or relieve stressconcentration at the welded portion 14, and hence to more certainlyprevent breakage of the welded portion 14 due to stress concentration atthe welded portion 14 when a torsional torque or a pushing force isapplied from the second wire 3 to the first wire 2.

The portion, having a nearly constant outer diameter, of the projection15 may be replaced with a portion having a smooth circular-arc shape.

FIGS. 11 to 13 show modifications of the projection of the guide wire ofthe present invention, in each of which the proximal side and the distalside of a projection are formed into shapes asymmetric to each otherwith respect to the welded surface (connection end face 21, 31) of thewelded portion 14.

FIG. 11 shows another modification of the projection of the guide wireof the present invention. As shown in this figure, on the distal end(first wire 2 side) from the welded surface of the welded portion 14,each of one side (upper side) and the other side (lower side) of aprojection 15 is formed into an approximately circular-arc shape inlongitudinal cross-section which is similar to that described in each ofthe previous embodiments, whereas on the proximal side (second wire 3side) from the welded surface of the welded portion 14, each of one sideand the other side of the projection 15 is formed into a curved shapesmoothly recessed in the direction from the welded portion 14 to theproximal end in longitudinal cross-section. In addition, the weldedportion 14 is located at a portion, having the maximum outer diameter,of the projection 15.

With this configuration, it is possible to smoothen transition ofrigidity and prevent or relieve stress concentration at the proximal endportion of the welded portion 14, and hence to more certainly preventbreakage, deformation, or the like of the proximal end portion of thewelded portion 14 due to stress concentration when a torsional torque ora pushing force is applied from the second wire 3 to the first wire 2.

FIG. 12 shows a further modification of the projection of the guide wireof the present invention. A projection 14 according to this modificationhas a configuration reversed to that of the projection 15 shown in FIG.11. As shown in this figure, on the proximal side (second wire 3 side)from the welded surface of the welded portion 14, each of one side(upper side) and the other side (lower side) of the projection 15 isformed into an approximately circular-arc shape in longitudinalcross-section which is similar to that described in the previousembodiments, whereas on the distal side (first wire 2 side) from thewelded surface of the welded portion 14, each of one side and the otherside of the projection 15 is formed into a curved shape smoothlyrecessed in the direction from the welded portion 14 to the proximal endin longitudinal cross-section. The welded portion 14 is located at aportion, having the maximum outer diameter, of the projection 15. Therecessed curved shape in FIG. 11 and FIG. 12 may be replaced with aproximally constant taper shape.

With this configuration, it is possible to prevent or relieve stressconcentration at the distal end portion of the welded portion 14, andhence to more certainly prevent breakage, deformation, or the like ofthe distal end portion of the welded portion 14 due to stressconcentration when a torsional torque or a pushing force is applied fromthe second wire 3 to the first wire 2.

Of course, on each of the distal side and the proximal side from thewelded surface of the welded portion 14, each of the one side and theother side of the projection 15 may be formed into a curved shapesmoothly recessed in the direction separating from the welded portion 14in longitudinal cross-section.

FIG. 13 shows a further modification of the projection of the guide wireof the present invention. As shown in this figure, a projection 15 isformed into an approximately circular-arc shape similar to thatdescribed in the previous embodiments as a whole; however, in thisprojection 15, the welded surface of the welded portion 14 is offset tothe proximal side (second wire 3 side). Reversely, in this projection15, the welded surface of the welded portion 14 may be offset to thedistal side (first wire 2 side).

With this configuration, since the welded surface of the welded portion14 is not located at a central portion of the projection 15 in the axialdirection, that is, it is out of the maximum outer-diameter portion ofthe projection 15, it is possible to prevent or relieve stressconcentration at the welded portion 14, and hence to more certainlyprevent breakage of the welded portion 14 due to stress concentration atthe welded portion 14 when a torsional torque or a pushing force isapplied from the second wire 3 to the first wire 2.

The configuration that in the projection 15, the welded surface of thewelded portion 14 is offset onto the proximal side or the distal sidemay be applied, for example, to the configuration that each of one sideand the other side of the projection 15 is formed into a non-circular(non-circular arc) shape in longitudinal cross-section as shown in FIG.10.

As described above, by making the shapes of the proximal side and thedistal side of the projection 15 asymmetric to each other with respectto the welded surface of the welded portion 14, it is possible toprevent or relieve stress concentration at the welded portion 14, and tomore certainly prevent breakage of the welded portion due to stressconcentration at the welded portion 14 when a torsional torque or apushing force is applied from the second wire 3 to the first wire 2.

FIG. 14 shows a further modification of a portion, in the vicinity ofthe welded portion, of the guide wire of the present invention. As shownin this figure, a portion, in the vicinity of a joining portion (weldedportion 14) between the first wire 2 and the second wire 3, of the guidewire is thinner than the remaining portion, and a welded portion 14 anda projection 15 are formed in a mid portion of a thinned portion 19 inthe longitudinal direction.

With this configuration, it is possible to prevent or relieve stressconcentration at the welded portion 14, and hence to more certainlyprevent breakage of the welded portion 14 due to stress concentration atthe welded portion 14 when a torsional torque or a pushing force isapplied from the second wire 3 to the first wire 2.

Preferably, the maximum outer diameter of the projection 15 is equal toor less than the outer diameter of a portion on the proximal side ordistal side from the thinned portion 19. This is effective to furthersmoothen movement of the guide wire relative to a catheter.

In the configuration shown in FIG. 14, the shape of the projection 15 isnearly equal to that shown in FIG. 10; however, the shape of theprojection 15 may be either of the shapes shown in FIG. 1 and FIGS. 5 to13.

The configuration of each of the modifications shown in FIGS. 11 to 14may be applied to either of the first, second, and third embodiments. Inparticular, the configuration of each of the modifications shown inFIGS. 11 to 14 may be applied to the projection 17 described in thethird embodiment shown in FIG. 6.

While the preferred embodiments of the present invention have beendescribed using specific terms, such description is for illustrativepurposes only, and it is to be understood that changes and variationsmay be made without departing from the spirit or scope of the followingclaims.

The entire disclosure of Japanese Patent Application No. 2002-244316filed on Aug. 23, 2002, Japanese Patent Application No. 2002-355907filed on Dec. 6, 2002 and Japanese Patent Application No. 2003-156010filed on May 30, 2003 including specification, claims, drawings, andsummary are incorporated herein by reference in its entirety.

1. A guide wire comprising: a first wire disposed on a distal side ofsaid guide wire; a second wire disposed on a proximal side from saidfirst wire; said first wire and said second wire being joined to eachother by welding; a weld portion formed by the welding has a projectionprojecting outwardly in a outer peripheral direction; and a proximalside portion and a distal side portion of said projection possessingshapes that are asymmetric to each other with respect to a weldedsurface of said welded portion at which a proximal end of said firstwire and a distal end of said second wire are welded to each other.
 2. Aguide wire according to claim 1, wherein said welded surface of saidwelded portion is located at a portion of said projection having amaximum outer dimension.
 3. A guide wire according to claim 1, whereinsaid welded surface of said welded portion is located at a positionother than a maximum outer dimension of said projection.
 4. A guide wireaccording to claim 1, wherein the distal side portion of said projectionpossesses an approximately circular-arc shape in longitudinalcross-section, and the proximal side portion of said projectionpossesses a curved shape in longitudinal cross-section that is differentfrom the approximately circular-arc shape.
 5. A guide wire according toclaim 4, wherein said welded surface is located at a portion of saidprojection having a maximum outer dimension.
 6. A guide wire accordingto claim 1, wherein said proximal side portion of said projectionpossesses an approximately circular-arc shape in longitudinalcross-section, and said distal side portion possesses a curved shape inlongitudinal cross-section that is different from the approximatelycircular-arc shape.
 7. A guide wire according to claim 6, wherein saidwelded surface is located at a portion of said projection having amaximum outer dimension.
 8. A guide wire according to claim 1, whereinsaid projection possesses an overall approximately circular-arc shape inlongitudinal cross-section.
 9. A guide wire comprising: a first wiredisposed on a distal side of said guide wire; a second wire disposed ona proximal side from said first wire; said first wire and said secondwire are joined to each other by welding; a welded portion formed by thewelding possesses a projection projecting outwardly in the outerperipheral direction; portions of said first and second wires in avicinity of said welded portion comprise thinned portions; and saidprojection being provided on said thinned portions of said first andsecond wires.
 10. A guide wire according to claim 9, wherein a proximalportion of said second wire on a proximal side of said thinned portionof said second wire possesses a greater outer diameter than said thinnedportion of said second wire, and a distal portion of said first wire ona distal side of said thinned portion of said first wire possesses agreater outer diameter than said thinned portion of said first wire,said projection possessing a maximum outer diameter that is equal to orless than the outer diameter of said distal portion of said first wire.11. A guide wire according to claim 9, wherein a proximal portion of thesecond wire on a proximal side of the thinned portion of the second wirepossesses a greater outer diameter than the thinned portion of saidsecond wire, and a distal portion of said first wire on a distal side ofsaid thinned portion of said first wire possesses a greater outerdiameter than the thinned portion of said first wire, said projectionpossessing a maximum outer diameter that is equal to or less than theouter diameter of said proximal portion of said second wire.
 12. A guidewire according to claim 9, wherein a proximal portion of said secondwire on a proximal side of said thinned portion possesses a greaterouter diameter than said thinned portion of said second wire, and adistal portion of said first wire on a distal side of said thinnedportion of said first wire possesses a greater outer diameter than saidthinned portion of said first wire, the projection possessing a maximumouter diameter that is equal to or less than the outer diameter of saiddistal portion of said first wire and the outer diameter of saidproximal portion of said second wire.
 13. A guide wire according toclaim 12, wherein a welded surface of said welded portion at which saidfirst and second wires are joined to each other by welding is located ata portion of said projection having a maximum outer diameter.
 14. Aguide wire according to claim 9, wherein a welded surface of said weldedportion at which said first and second wires are joined to each other bywelding is located at a portion of said projection having a maximumouter diameter.